Improvement in indicators for steam-engin



H. TABOR. Indicator for Steam-Engines, 8210.

No. 210,643. Patented Dec. 10, 1878.

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' 7 r r I N,PETRS, PNOTO-LITHOGRAPHER WASH] UNITED Srnrns PATENT OFFICE.

HARRIS TABOR, OF CORNING, NEW YORK.

IMPROVEMENT IN INDICATORS FOR STEAM-ENGINES, 81,0.

Specification forming part of Letters Patent No. 210,643, dated December10, 1878; application filed October 30, 1878.

To all whom it may concern:

Be it known that I, HARRIS TABOR, of Corning, in the county of Steubenand State of New York, have made an invention of certain new and usefulImprovements in Indicators, parts of which are applicable to otherpurposes and that the following, taken in connection with theaccompanying drawings, is a full, clear, and exact description andspecification of the same.

The object of this invention as applied to indicators is to reduce thenumber and weight of the reciprocating moving parts of the instrument,and consequently to render it more accurate and better adapted to recordthe action of steam when the engine to which the indicator is applied isrunning at a high rate of speed.

To this end my invention consists of certain combinations of thevibratable or vibrating indicator-lever, or its substitute, with certaindevices for causing the point thereof to describe a straight line,notwithstanding the fact that the lever vibrates and varies itsinclination to a central line. These combinations are recited in detailin the claims at the close of this specification.

In order that they may be fully understood, I have represented in theaccompanying drawing, and will proceed to describe, a steam-err gineindicator embodying myinvcntion in the best form in which I haveembodied it at the present date.

Figure 1 of said drawings represents an elevation of said indicator.Fig. 2 represents a section of a part thereof.

The cylinder A of the indicator represented in said drawings is of theusual construction, and is fitted with a piston, 13, which is pressedagainst the steam under the piston by the spring 0. The movement of thispiston by the varying pressure of the steam on one side and by thespring on the other indicates the varying pressure, which is recorded bythe action of a pencil-point upon a sheet of paper. The sheet of paperis supported upon the paperroller 1), which is secured at one side ofthe indicator-cylinder A, and is fitted with a cordpulley, 0, so thatthe paper-roll may be turned to and fro on its axis in the usual mannerat each revolution of the steam-engine by means of a cord connected withsome moving part of the engine.

The pencil is so held by the vibrating or vibratable lever F that thepencil-point bears upon the surface of the paper on the paperroll. Thislever F is connected with the piston B, and also has its fulcrumconnected with the indicator-cylinder, so that the lever vibrates withthe movements of the piston. In order that the pencil end of the lever Fmay describe a straight line parallel with the axis of the paper-roll,the lever is combined with the piston 13 through the intervention of alink, G, whose lower end is jointed to the piston, whose upper end isjointed to the indicator-lever, and which has a curved body, H, that isguided by the stationary guide I, which, in this example, is secured inthe opening of the cylinder-head J. The guide I has in this case theform of a round pin, extending crosswise through a curved guide-slot, s,in the guide-body H and the action of the station: ary guide upon thisguide-slot causes the link to move laterally to and fro as the pistonmoves it up and down. The lateral movement of the link compels theindicator-lever to which it is jointed to move endwise as it vibrates upand down, and thus causes the outer or indicating end of the lever todeviate from the are of a circle. In order that the lever may bepermitted to move endwise as it vibrates, its fulcrum-pivot i isconnected with the indicator-cylinder by a swinging link, Z; and inorder that the indieating or pencil end of the lever may move in astraight line, the guide-slot s is made of the proper curvature to givethe lever the necessary endwise movement for that purpose. Thiscurvature may he laid out geometrically, or it may be readily obtainedby holding a pencilpoint or a scratch-awl at one side of a blank orunslotted guide-body in the position of the center of the guide-pin I,and by moving the lever up and down with a point in its indicating endfollowing a straightedge. The pencil or seratch-awl will then describe acurve upon the side of the blank guide-body, and this curve will be themiddle line of the slot of proper curvature.

In this combination of the lever with the curved guide-body and guidethe link performs the function of connecting the lever with theindicator-piston, while the curved guidebody and guide compel theindicating end of the lever to describe a straight line. The connectionof the piston and lever is direct, and the moving parts are reduced tothe smallest possible number, and their combined weight is also small.

The steadiness with which the apparatus operates in practice isremarkable, even when indicating the pressure of the steam in thecylinders of steam-engines making upward of two hundred revolutions perminute.

The construction of the instrument may be considerably varied withoutceasing to embody my invention. Thus, for example, in place of arrangingthe indicator-lever to vibrate on a fulcrum-pivot connected with thecylinder by a'swinging link or stanchion, the fulcrumpivot may beconnected with a fixed stanchion, and the fulcrum end of the lever maybe constructed to slide endwise through or upon the fulcrum-pivot. Thecurved guide-body also, instead of being intermediate between the leverand the piston, may form an extension of the guide-link above the lever,the guide in such case being also arranged above the lever and held inplace by a suitable stay or support. The curved guide-body need notnecessarily form a part of the link, because the guide-body and guidemay be transposed, the former being fixed to the head of the cylinder,while the latter is carried by the vibratable lever, or by a plain link,and traverses the curved guide-slot of the guide-body, so that the leveris caused to move endwise, and the pencil-point may be compelled to movein a straight line. The guide-body also may have the cross-section of arod, while the guide has the form of an eye, through which theirodformed body slides; but in this case the guide should be permitted toturn on an axis crosswise of the direction of motion of the guidelink,so as to adapt the position of the guiding-eye to the varyinginclination of the curved body of the link. When the guide-body has acurved guide-slot running on a guide-pin, the edges of the body itselfneed not necessarily be curved, it being essential only that the portionof the curved guide-body upon which the guide operates shall have theproper curvatum.

The lever, curved guide-body, guide, and link may be used for otherpurposes than an indicatoras, for example, to combine two devices whichare to reciprocate parallel with each other,but with difl'erent lengthsof strokeand I intend to use this combination wherever its use isexpedient. I

- I claim as my invention 1. The combination, substantially as beforeset forth, of the vibratable lever, the link, the

curved guide-body, and the guide.

2. The combination, substantially as before set forth, of the piston,the link, the curved guide-body, the guide, and the vibratable 1c thepaper-roll. p

In witness whereof I have hereto set my hand this 17th day of October,A. D. 1878.

HARRIS 'rABon.

Witnesses:

A. N. SILL, DAVID W. PAYNE.

